Control of food spoiling micro-organisms, particularly on processed food stuffs, is an ever present concern in preserving food products. Various approaches such as aseptic packaging and pre-fill and post-fill sterilization are applied as a possible control method but they often result in undesirable changes in food quality characteristics. In addition fresh and many minimally processed foods cannot be preserved by such approaches and must rely on other methods. Washing in antimicrobial solutions is one possibility but protection during storage and distribution is still necessary. Incorporating antimicrobial agents in the food is another option but requires relatively large amounts of additive that increase cost and may lead to undesirable off-flavours. Modified atmosphere packaging is a common method to extend the shelf life, particularly of fresh produce, by reducing the rate of food deterioration achieved by modification of the initial concentrations of oxygen and carbon dioxide inside the package. However, these modified gas concentrations change with time. Also, some microorganisms can grow in the absence of oxygen and for some foodstuffs the absence of oxygen can affect freshness and flavour perception and even encourage the growth of harmful anaerobic microorganisms. Thus an antimicrobial agent is usually required. Synthetic antimicrobial agents in or on foodstuffs are usually not acceptable by consumers, as they prefer natural foods and food components. These additives may also accumulate above safe levels and affect flavour and taste. Antimicrobial agents are often active only against a selected range of microorganisms and those that are active against Gram-positive bacteria may not be active against Gram-negative bacteria and/or yeasts and/or moulds.
Incorporation of antimicrobial agents into packaging materials, particularly packaging films has been proposed in the past. These have generally been synthetic antimicrobial compounds. Migration of these compounds from the films into the food can be unacceptable. Generally, food safety and packaging regulations prohibit the release of (active) additives that are not approved for food content or they limit the allowable migration of such active additives from the packaging material.
USA patent application 2002/0051754 discloses an antimicrobial packaging polymer which incorporates quaternary ammonium and phosphonium salts.
There are plant extracts that possess antimicrobial activity and which are approved for use with foods. Some of them, like allyl isothiocyanate (AIT), posses a repelling smell causing unacceptable off-flavours.
Japanese abstract 03145406 discloses a rodent repellant which mixes an essential oil with an organic polymer including rubber and wood.
U.S. Pat. No. 5,688,509 discloses a controlled release insecticide for repelling insects from food, tobacco and other consumables. The active agent is incorporated in a controlled release carrier at a content above 1%.
WO00/69277 discloses an antimictobial agent for treating swine dysentery and diseases of hoofed animals using a combination of carvacrol an essential oil from oregano and thymol an essential oil from thyme.
USA application 2004/0071757 discloses an antiviral patch made by the addition of an essential oil to a pressure sensitive adhesive in concentration levels above 1%. Basil contains essential oils that exhibit activity against both Gram-positive and Gram-negative bacteria as well as against yeasts and moulds. The major active constituents of basil oil from various sources (basil varieties) are linalool, methylchavicol, citral, geraniol, methyl cinnamate, methyl eugenol, 1,8-cineole and trans-a-bergamotene. The two major components of basil, linalool and methylchavicol, possess very weak smells, not detectable at low concentrations. As the active basil oils are volatile and much of them may be lost during mixing and processing of the polymer into a packaging material, special precautions and procedures have to be followed.
It is an object of this invention to provide an antimicrobial packaging film, coating, container, or packaging component, such as labels, that uses a natural food acceptable agent in a food grade packaging material.